The present invention relates to a system consisting of an interchangeable battery for a battery-operated electric tool and two chargers for the interchangeable battery.
Hereinafter, a charger provided with exposed counter-contacts will be called, by way of example, a transformer charger, and a charger provided with shielded counter-contacts will be called, by way of example, a condenser charger.
The charging of interchangeable batteries by means of transformer chargers has the advantage that no substantial precautions are necessary against the unintentional touching of the charger's contacts, since the voltage is reduced to a low level that is not dangerous to humans, i.e. about that of the battery's cell voltage or sum of the cell voltages. On the other hand, the charging circuit of condenser chargers operates at line voltage, which means that according to safety regulations, the contacts of such a charger must be protected against unintentional touching. Due to the large size of condensers, condenser chargers used to require much effort to manufacture and were very expensive. However, in recent times, the development of condensers has progressed so far that there is now an economically feasible interest in using condenser technology when recharging interchangeable batteries.